As part of the world-wide interest in alternate power sources, some consideration has been given to electric-powered propulsion systems for vessels. Batteries as electric storage devices have some advantage as being relatively small unit size and relatively easily securely mountable. As such they can serve not only as power reservoirs but also as ballast, a requirement for vessel stability.
However, batteries must constantly be recharged, and the power capacity does not match the energy density of gasoline. For example, gasoline has an energy density around 14, while lead-acid batteries are around 3. Nevertheless, as compared to larger engines directly powering the screw, hybrid designs comprising a small diesel engine powering a generator for the purpose of recharging the batteries poses potential for recreational motor cruisers.
For electric, or hybrid electric/small engine-powered motor cruisers, the critical limitation is hull drag. For a gasoline or diesel-powered ship engine, the energy density of the fuel is such that low drag hull design is less of a consideration than accommodations, amenities and speed.
For a cruising yacht to function effectively under electric power, it must be highly efficient, seaworthy, stable, and comfortable. A double ended hull form would meet the first two criteria admirably. However, narrow, un-ballasted hulls typically have low load capacity and roll readily and uncomfortably. Further, they do not provide dockside stability that is required for useful cruiser design to be accepted by discriminating owners and users. In addition, accommodations suffer due to lack of beam, a double-ender typically being notoriously narrow. Finally, the fine (sharp or pointed) prow and stern ends, while good for wave piercing, do not dampen pitching very well during cruising.
Accordingly, there is a need in the art for a cruiser hull design that is highly power efficient so that it may be fitted with hybrid electric/small engine, or all electric power sources, yet provides ample beam for accommodations, while being stable, both dockside for boarding and disembarking and during cruising, resists roll and pitch yet cruises at an acceptable speed.